Centralized traffic control system for the code control of interlocked switches and signals



Nov. 20, 1951 F. T. PASCOE ET AL 2,576,038

CENTRALIZED TRAFFIC CONTROL SYSTEMS FOR THE CODE CONTROL OF INTERLOCKED SWITCHES AND SIGNALS Filed Nov. 9, 1946 6 Sheets-Sheet l 42 ZLA 2113 11 ZLB 4 M 611E 21 6 921212 T9 T2 51 6 lam? 5652 501 7051? 1573 552? @5522? 0 7572 Fly. 1.4.

mm 25452, 1650 am my 7011: 6 my 11 Elm-x JZVE IKE JOEE 2545 JZVW6FT @C JHWK a gig 55 2 .5224 2 B ,iHEB 2150's 121% 21%; 1111K 7 I rm W 9 EB 2115' 2115 INVENTORS Fran .Parcae and AFL L .Je ome. BY

THEIR A'i'TORNEY Nov. 20, 1951 T PA OF INTERLOCKED SWITCHES JASM 545M I: ISM $35M SCOE ET AL SYSTEMS FOR THE CODE CONTROL.

AND SIGNAL S 6 Sheets-Sheet 4 til - Fl 24. 4 4311; 51v? 431 61m film 651125 c 0 b Jr 0 e b c Y 511W! B a pm; 533F201 a 2 1;? I IIZWP mm? 25129 0 21%? a 515m 5mg, 0 e H e 48 41115 612 11 6215' 5L l F a f 1 my 41:4 6216' c 4116p I I I 615146 hmfl 31 6126p y l 3 a I 5L1: 1VWP 6M5 i 5 3 F j 0' a fi M Pa n3 @f kb 2 x 2 mm 6MP i O C 5 21122 mm 3m 52m 71110 7 B b 0 0 (I g I 02 B 21g: 2g ZLAG 2mm l W M 2L6! 12" INVENTORS THEIR. 'ATTORNEY' Nov. 20, 195] T PASCOE ET AL F. CENTRALIZED TRAFFIC CONTROL SYSTEMS FOR THE CODE. CONTROL OF INTERLOCKED SWITCHES AND SIGNALS 6 Sheets-Sheet 5 Filed Nov. 9, 1946 I 1 52 [115' I 1 .1132 0 I 514498 IWSR mm U a -JWW mid P...

Patented Nov. 20, 1951 OENTRALIZED TRAFFIC CONTROL SYSTEM FOR THE CODE CONTROL OF INTER- LOCKED SWITCHES AND SIGNALS Frank ,T. Pascoe, Carnegie, and Arthur L. Jerome, Edgewood, Pa., assignors to Westinghouse Air Brake Company, a corporation of Pennsylvania Application November 9, 1946, Serial No. 708,920

14 Claims. 1

' Our invention relates to centralized traffic control systems for railroads, and more particularly, to railway trafiic controlling apparatus for the control of electrically interlocked track switches and railway signals from a control oflice.

Our invention is particularly adapted for use in connection with a selective communication system of the code type, such, for example, as the remote control system shown in Letters Patent of the United States, No. 2,229,249, issued January 21, 1941, to Lloyd V. Lewis, and-in its specific embodiment as disclosed herein, our invention is illustrated as arranged for use in the system of this patent.

In remote control systems of this type, the components are assembled in the form of individual storage units each identified by a selective code call. Each storage unit in the field is adapted to control and indicate a group of traflic governing devices, such as a power operated track switch and the railway signals which gov ern trafiic movements over the switch, and is linked, by means of its code call, with a corresponding storage unit in the .ofiiceicontrol machine which governs the transmission of control codes for effecting the operation of thelswitches and signals in accordance with the positions of their control levers. Each control code is initiated by pressing an individual starting button associated with the control levers of the corresponding group, and includes in addition to the code call a group of code elements reflecting the position of each of the levers of the group.

Each oflice storage unit also includes agroup of indication stick relays which respond to indication codes transmitted by the station storage unit having the same code call, to indicatenthe condition of the switch and signals of the cor:- responding group and for also indicating the con: dition of one or more track sections. Furthermore, the system is arranged to transmit the codes one at a time over a single line circuit, without interference, codes originating at the, same time, or while the line circuit is inuse, being transmitted one at a time in a given -orderof code superiority. 4

In the application of the remote control system to the control of trafiic on single track railroads, where generally each station includes only one track switch, the preferred mode of operation is to include elements for changingthe position of the switch and for clearing a signaliwhich governs train movements over the switchin the same control code. On the other hand, in the application of the system to interlocked track layouts including a plurality of track switches this so'- controlled by different codes, making it desirable to delay the transmission of the signal clearing code until indications have been received that each switch of the route has assumed the desired position. In such cat-cs an individual code mode of operation is generally used, requiring two successive codes, at least, to operate a switch and to clear a signal even though they are governed by the same storage unit.

The principal object of the present invention is toextend the composite code mode of operation to layouts involving a plurality of track switches and signals in order not only to provide a uniform mode of operation when the controlled territory includes both single switch and multiple switch layouts, but also to enable the routes to be set up by the transmission of the minimum number of codes and with a minimum of effort.

In accordance with our invention the control apparatus at the office is so arranged that any route through a track layout involving one or more track switches may be set up by positioning the swtich levers to indicate the route desired, reversing the signal lever for the entering signal, and then pressing the starting button associated with the operated signal lever.

Each starting button when depressed always establishes a circuit for energizing the starting relay for the storage unit with which the starting button is associated, while each starting button when depressed may also establish circuits for energizing the starting relays for one or more additional storage units so that all or the control codes necessary to establish a complete route are initiated by pressing of a single starting button. Each of the circuits governed by a starting button for energizing a starting relay for an additional storage unit is automatically controlled so as to be established only when the starting button is pressed to establish a route which requires transmission of a control code by the additional storage unit to thereby insure transmission of all essential control codes and at the same time prevent transmission of unnecessary control codes.

In case the establishment of the desired route requires the operation of a switch and of a signal controlled by the same storage unit, but does not require the operation of any other switch, the pressing of the appropriate starting button initiates the transmission of a single composite code, as heretofore, but if it requires a change in the position of one or more switches controlled by different storage units, a lockout relay associated with each such unit becomes energized causing the transmission of the proper codes for operating the switches controlled thereby. In addition, each lockout relay which becomes energized delays the transmission of the stored signal clearing code until an indication code is reof several dilferent control'c'odes'is required in' order to set up the route.

A further feature is that each additional code is. initiated only when the'indicated position of the switch controlled thereby does not correspend with the position of its controllever, there- 7 by avoiding the transmission of idle codescontaming control elements for switches whichalready occupy the required positions.

One object attained by our invention is the provision of improved means'for insuring that thecode for clearing the signal will be the last of the series of route establishing codes to be transmitted, regardless of the order of superiority of the different codes, and in this're'spect our invention is an improvement upon that disclosed in an'appli'eation for Letters Patent of the United States, Serial No. 649,598, filed February 23, 1946; by Arthur L. JeromaLloy'd V. Lewis'and Frank T. Pascoe', for Centralized Traffic Control Systems.

A feature of our invention comprises the control of codes" for governing the signals by a systernof signal clearing relays controlled'jointly by the" signal levers and the associatedstarting buttons," which is an improvement upon that disclosed in an applicationfo'r Letters Patent of the United States, Serial No; 648,716, filed February 19', 1946yby James I. Grammer, for Contralized Trafl'lc Control Systems. A's disclosed herein, these relays res-pond immediately when the" corresponding. starting buttons are operated, but they'are soeontrolled over a system'of interlocked circuits that each can be pickedup to establish a route" only when none of the switches of such route are included ma conflicting route having its signal clearing relay energized;

another feature of our invention is tlieprovision of means for transmitting codes foroparatihg each or thesw itchs' individually without opcrating any signal clearing relay, which means is effective only when all ofthose signal clearing relays are released which govern routes over the switch even though' they are controlled by diffrent stcra'ge units. a

A further feature'tof our' invention is the provision' of means at th'eswitch location forprevenb "ception of a switch operating code after I espondihg detector track section is occup ie regardless of the position of the detector trac'l; relay, untilfan indication of the occupants of the section has been transmitted to the oifice, eee he w th. eans a e me se edby this indication for preventing further tra'nsmis-j sion of codes for operating the switch until an indication" is received that the detector section hasbeen vacated. v a V Other objects, purposes and features of our invention will be point'ed out as the description proceeds;

One form of apparatus embodying our inven-' tion' will now bdescribed, and the novel features thereof will then be pointed out in claims. y

Referring to the accompanying drawings, Fig. 1A shows the' operator's control panel; Figs. 1B tolH, inclusiveshow the circuits and apparatus associated therewith at the control ofiloe; Fig. 2A shows a typical track layout chosen to illus trate our invention; Figs. 2B to 2H and Fig. 2J

show the wayside circuits and apparatus; and

4 Fig. 3 illustrates the indication system of the Lewis patent hereinbefore referred to in condensed form.

Similar reference characters refer to similar parts in each of the views. 2 To simplify the circuits, we have herein shown only the terminals'of the sources of current for energizing the various relays, the reference character B designating the positive or supply terminal and the reference character C the negative or'common return terminal of the local source of current, in each instance.

To illustrate our invention, we have shown haeman interlocking control system of a con ventional type in which all operations for the protection of trailic movements are controlled locally by safety type relays and are governed by communication type relays controlled from ajcem tral ofilce by a remote control system which is also oi a conventional type;

Our invention is embodied principally in apparatus located at the control office and interposed in the remote control system between'the operators levers and code starting buttons,

- shown in Fig.11A, and the code initiating and signal lever, shown in Fig. 1D, and a code lock out relay CLO for each switch lever, shown in Fig. 1G. These relays are governed in accordance with Wayside conditions by the remote con"- trol system indication relays shown in Fig.=3, which also control the indication lamps of Figs; 1A and 13. Additionally, the remote control. system includes a code indicator relay CK, Fig. 1C,

in'each ofilce. storage unit,'not shown in the remote control system patent.

Wheniour invention is used the operator is enabled to'set up any of the routes and to clear the signal therefor by positioning the switch: levers to indicate thev course of the route and by reversing the signal lever for the signal which governs train movements over the route in the desired direction, and then' initiating code transmission by pressing the starting button associated with that, signal lever.

When this-starting button" is operated, the cor- 'I he energized signal clearing relay completes a stick'circuit over which it is held energizedindependently of the route circuits, and operates contacts in Figs. 1D, 1E, 1F, 1G and 1H, tho'se'in' Fig; 1D serving to o en the route circuits for routes which conflict with the one being estab fished. In Fig. 1G, the relay CEO for each Switch of the route becomes energized, but only if its switch lever has been moved and is out of correspondence with" the indicated position of the a It follows that the energized relays CLO indicate which switches need to be moved to set up the desired route. These relays also operate con-- tacts in Figs. ID, 1E, 1F, 1G and 1H.

In Fig. IF, the starting relay ST for the signal clearing code is picked up directly by the operated relay PBR, and contacts closed by the energized relays CLO enable this relay to pick up one or more additional relays ST if the transmission of switch control codes thereby is necessary in order to complete the desired route. Each relay ST picks up the corresponding relay CK in Fig. 1C, which serve to hold the energized relays CLO picked up. Each relay CLO is held energized until an indication code is received which indicates that the position of the associated track switch corresponds to the position of its switch lever.

The contacts of the energized relays CLO in Fig. 1D prevent the energization of any signal clearing relay for a route over a switch which is being operated, and in Fig. 1F, govern the code initiating circuits controlled by the starting relays in such manner as to delay the transmission of the signal clearing code for the route being established until the other control codes involved have been transmitted and indications have been received that the desired route is set up. The energized signal clearing and lock out relays govern the character of the switch and signal control elements in these codes by the operation of contacts in Fig. 1H.

The energized signal clearing relay is released by a track indication relay TK when a train occupies the route, or it may be released by the transmission of a code for putting the signal to stop.

Having thus described the principal features of our invention, we will now describe the system in detail.

The wayside circuits and apparatus As disclosed herein, the apparatus of our invention is arranged to control the switches and signals of the track layout shown in Fig. 2A, which comprises the two main tracks of a double track railroad connected by the crossover switches 3AW--3BW and 5AW-5BW, the lower track also including two single switches IW and 1W. Main line train movements over the tracks of the layout are governed by the high speed signals ZRA and GLA, and other movements by the slow speed signals ZRB, ZRC, ZLA, ZLB, 4R, BR, and SLB, located as shown. The tracks are divided into sections by insulated joints to form the detector track sections IT, 3T, ST and IT, each having the usual track circuit provided with a normally energized track relay ITR, 3TB, etc. The track relays TR govern the line relays ZRHD and BLHD of Fig. 2C, the signal control relays RHS and LHS of Fig. 2D, the locking circuits of Figs. 2G, 2H and 2J, and also govern the transmission of indications of track conditions to the office in the manner shown in Fig. 3. The track switches are arranged for power operation by the provisions of suitable switch machines ISM, 3ASM, etc., which are controllable, under proper conditions as reflected by the switch locking relays LR of Fig. 2J, by polarized switch operating relays IWZ, BA-WZ, etc., over circuits arranged as shown in Fig. 2E. Each switch is also provided with a suitable overload relay 0R, as shown, these circuits being arranged as shown and described in Letters Patent of the United States No. 2,124,601, issued July 26, 1938, to Norman F. Agnew, et al., for Railway Switch Controlling Apparatus.

In Fig. 2E, and likewise in other views involving a plurality of similar sets of circuits only one set of each type is shown in detail. Thus it is to be understood that the circuits for relay IWZ, for example, controlling switch 1W, are similar to 6; those for relay IWZ, and that those for the cross over switches 5AW-5BW are similar to those shown for the switches 3AW3BW.

Each switch operating relay WZ in Fig. 2E is controllable under proper locking conditions by a code controlled switch control relay, such as the relay IWSR, Fig. 2D, which is of the stick polar type. This relay replaces the pair of neutral stick relays NWS and RWS of Fig. 8 of the Lewis patent, the switch control relays WSR being controlled over wires 31 and 32, corresponding to the similarly designated wires in Fig. 7 of the patent, by codes which reflect the positions of the corresponding switch levers, such as lever ISW of Fig. 1A.

Each switch machine such as ISM together with the associated switch operating and control relays WSR and W2, controls a polarized switch indication relay WP, and normal and reverse reeating relays NWP and RWP, shown in Fig. 2F. The circuits of Fig. 2F are arranged as shown and described in Letters Patent of the United States No. 2,351,495, issued June 13, 1944, to Arthur E. Dodd, for Electrical Control Apparatus. Each switch repeating relay such as INWP or IRWP when energized indicates that the associated switch or crossover, as the case may be, is locked in the normal or reverse position, respectively, and also that the associated switch operating and control relays are in the corresponding normal or reverse position. The switch repeating relays NWP and RWP govern the route circuits of Fig. 2B, the signal circuits of Fig. 20, the locking circuits of Figs. 2G, 2H and 2J, and also govern the transmission of indications of switch position to the ofiice as shown in Fig. 3, for controlling the switch indication relays such as relays INWK and IRWK, which indicates the switch position by the lighting of a lamp INE or IRE located above the switch lever and shown in Figs. .1A and 1B, and also govern circuits shown in Figs. 1D, 1F, and 1G.

It is to be understood that the remote control system is so arranged that an indication code is initiated by a station storage unit whenever a change occurs in the position of one of the wayside relays which govern it or when a control code is received by that unit. Relay IMSP picks up during the transmission of an indication code and establishes connections to the wires 4|, 43, 45, 41 and 44, which govern the character of certain of the code elements. When terminal B is connected to'any of these wires, energy is supplied at the office to the corresponding wires Ill, H3, H5, H1 and H4, and a delivery relay such as 234D positions the indication relays accordingly.

Referring now to Fig. 2A, it is to be understood that each of the signals there shown is of the well-known searchlight type, having a threeposition mechanism shown in Fig. 2C, and identifled by the reference character G prefixed by the designation of the signal, and controlled over a circuit network conforming to the track layout. The circuits for the mechanisms G are prepared by the energization of route relays, such as the relays 2RH and 2LH, which relays are controlled over route circuits shown in Fig. 2B, by the signal control relays RHS and LHS of Fig. 2D, and by the switch repeating relays NWP and RWP of Fig. 2F, in such a manner that each route relay RH or LH becomes energized in response to the energization of the corresponding signal control relay only when each track switch of the route governed thereby has assumed a position in agreement with that of its control relay WSR.

acrogoss .nsrshown in Fig. 2C, the mechanisms 2R-AG'an'd BLAG for the zhigh-speed signals *ZRA- a'nd :fiLAare reversibly controlled by polarized line relays 2-RHD and 6LHD in a conventionalmanner to indicate caution or proceed when energized in a-normal or reverse direction, anol to indicate stop when deenergized. The remaining signals ofEig. 2A govern slow speed movement's 'only, and alltheir mechanisms are arranged toindicate caution slow speed when energized and to-ind-i cate stop when deene'reized.

Each-group of signal riiecha-nisms in Fig. 2C controls-a stop indication repeating relay RGP =or LGP, which as shown is arranged-tube energized when all of the signals of its group indicate stop. These relays govern the-transmissionor signal indications by the code system. Thus as indi-- cated in Fig. 3, the release of relay 21GB or 2RGP, when one of the corresponding signals is cleared, initiates the transmission of an indication code as explained in the Lewis patent, resulting in the energization of the corresponding signal indication relay ZLHK or 2RHK, which as shown in Fig. 1B completesza circuit for lamp Z LE or ZRE and opens the circuit for lamp Z-NE.

Each signal repeating relay RiGP' or LGP together with the associated route relay RH or LH controls an approach or time looking stick relay RAS or LAS, shown in Fig. 2G, by which the switchesand signals are so inter-locked that on theone hand, the release of thefapproachlocking relay for any signal is n'ecessaryin order to enable such signal to be cleared, and on the other hand, the approach locking reday must occupy its energized position in order to enable any switch or" a .route governed by such signal to be operated, or to enable the opposing signal .for such route to be cleared. As shown in Fig. 2G, each approach locking relay is normally energiz'ed over a stick circuit which-includesa front contact I) of the stop indication repeatingrelay RGP or LGP for the associated signal or signals, shown in Fig. 2C, and a back contact b of the corresponding route relay RH or LH of Fig. 2B. When any route rel'aysu'ch as relay ZRI-I becomes energized to prepare-a signal circuit by closing its front contacts a and c in Fig. 2G,,the opening of its back contact 12 releases the associatedapproach locking relay such asire-lay 12 RAS, causing the latter relay to close its back contact b in the circuit of Fig. 2C prepared by relay Hill, for mechanism ZRAG, ERBG or =2-RCB;, for that -signal which governs traffic move ments over the established route.

As shown in Fig. 25 a switch lockingreda-y LR is providedior each switch section controlled by the track relay TR of the same section "and each relay LR when reelased prevents the operation of the associated switch control relay WSR, in Fig. 213, by opening its front contact e, and also locks the, switch or switches in its section by opening its front contacts a and c in the circuits for the corresponding switch operating relay WZ, shown in Fig. 2E.

Each approach locking relay such as relay ERAS, upon releasing opens itscontacts 12,- Fig. 2 .1, in the circuit for the switch locking relay for the first section of the route,- such as relay l'3'LR, to cause it to release, and also opens a contact which releases one or more of the sec tion locking relays of Fig. 2H, such as relays IES'; to cause the release of the relays LR for the succeeding sections of ,the route, such as relay SLR whenthe crossover switches SAW and 313W are reversed,.or relay 5- TLR. when these switches 81 aremnormal, thereby holding the relay LIE-for each section released to'lo'ck the switcheslo'catcd therein until a train occupying, the routereaches the corresponding section and locks?- the switches by the release of the "track relay TB thereof.

Returning now to Fig. 20, it will be seen thatv the clearing of any signal is made dependent not only upon therelease of the associated approavh locking relay as already explained but also upon the locking of the switches controlled thereby, the signal circuits prepared by the route relay QRH, for example, including aback contact b of the approach locking relay ERAS and also including back-contacts y of the relay LR-ior eachswitch of the route. Furthermoreeach signal circuit also includes a front contact I) of the approach. locking relay LAS or RAS-forthe opposing signal for the same route, thereby providing time and approach locking protection against the iinprover reversal of the direction of traffic movements.

Each of the signals, as shown, is-arranged who put to stop automatically when a train enters the first track section of its route, remaining at stop after the first section is vacated, .due to the release of the signal controlsrelay RHS tor LHS by the corresponding track relay TR, the signal control relay upon releasing causing the corresponding route relay RH or LE to release to open the signal circuit. 'The signal control relay circuit is also opened at the back contact d of a track storage reday TS shown in Big. 3, which relay picks up in response to the release of the associated, track relay TR. Each relay 118 controls the transmission of thetindica-tion over wires fiL-E il by which the corresponding track indication relayT-K at the office' is energized to light .a lamp TKE on the track diagram to indicate the occupancy of the controlling track section, and is held energized over aback contact of a Valve relay il-V, shown in Fig. 7' of the Lewis patent. Relay V is controlled in the same manner as relay 'ITK, becoming ener' gized when a track occupied code is transmit ted and releasing when a track clear" code is transmitted. The connection from terminal 13' r though the section is vacated. before the .sys-. 'tem has an opportunity to transmit the indication', as explained in the Lewis patent. Each track indication relay TK when energized, opens a back contact e, shown in Fig. which as hereinafter explained, prevents the transmission of code elements tor changing the position of the switch in the corresponding track section, and also opens a backcontact d, shown in Fig. 1D, which releases the corresponding -sig n-al clearing relay RGS or LGS, so that, after a, signal has beenput automatically to stop, it cannot be cleared again by the transmission of a signal clearing code until an indication is received that the first section of the route has been vacated. One purpose of this arrangement-is to prevent the-inadvertent recleari-n-g of a signal which has been put automatically tostop, in the event the transmission of the track occupied indication is delayed until after the controlling track section is vacated.

Referring again to Fig. 2G, it will be seen that when a signal is put automatically to stop by the release of the track relay for the vfirst section of a route, the approach locking relay for thatssi-gnal, such as relay 2RAS, is picked up in the usual manner over back contact c of the track relay ITR, the open front contacts e and f of which hold relays IES and l3LR released until the first section of the route is vacated. Each approach locking relay is also provided with the usual means for effecting its energization after a suitable time interval following the manual return of a signal to stop, comprising a time element relay of the thermal type, such as relay 2LTR, for each approach locking relay controlled by low speed signals only, or one of a motor or step by step type providing a longer time element, such as relay ZLTE, for the approach locking relays for high speed signals. In the latter instance, a normally energized approach relay such as relay ZRAR, which may be controlled as in Fig. 9 of the Lewis patent above referred to, provides means for nullifying the delay in the event the signal is put to stop when no train is appreaching.

Each relay TR when released holds the associated relay LR released only until the corresponding section is vacated, to provide the usual sectional release of the switch locking. In Fig. 2D, it will be noted that a back contact of the track storage relay TS above referred to is included in the circuit of the switch control relay WSR for each switch in the corresponding section, that is, the circuit of relay IWSR includes back contact 0 of relay ITS, and that of relay 3WSR includes back contacts 0 of relays ITS and 3TS. These contacts serve to prevent the reception of the switch control elements of a code while the switch section is occupied, prior to the transmission of an indication of its occupancy to the office. After the track occupied indication is transmitted, the transmission of code elements for changing the position of a switch located in an occupied track section is prevented by the opening of the back contacts of the track indication relay TK, in the circuits of Fig. 1H.

The circuits and apparatus at the control oflice It is to be understood that the remote control system includes the ofiice coding and storage units of Patent No. 2,229,249 and that these function as described in the patent except for such modifications as are pointed out herein.

As shown in Fig. 1A, the operators control board includes an illuminated diagram of the track layout and employs four ofiice storage units each having a starting button STB corresponding to the key SK shown in Fig. of the patent. One storage unit associated with the first panel at the left in Fig. 1A is assigned to the control of switch IW and signals 2RA, 2RB, ZRC, 2LA and 2LB, another to the control of the crossover switches 3AW and 313W, and of signal 4R, the third to the control of switches 5AW and 5BW and of signals 6R, SLA and ELB, and the fourth to the control of switch 1W.

Fig. 1B shows the circuits for the indication lamps for the first panel, while Fig. 3 shows the circuits for the indication stick relays of the corresponding office storage unit together with the contacts of the wayside relays by which these are governed in the manner described in the patent. It is to be understood that the indication relay and. lamp circuits for the remaining panels and oflice storage units, not shown, are similarly arranged.

The starting button STB for each panel which contains a signal lever controls a slow release repeating relay PBR, Fig. 1D, the purpose of which is to prolong the efl'ect of a momentary operation of the starting button'for a time suflicient to pick up two or three relays successively as the system of our invention requires under certain conditions. Each relay PBR, when energized momentarily, controls circuits in Fig. 1D to enable the signal clearing relays RGS and LGS of the corresponding unit to be picked up or released, depending upon the position of the controlling signal lever SG, and at the same time the operated relay PBR closes a circuit in Fig. IE to pick up the code starting relay ST for the unit. Each signal clearing relay RGS or LGS may be picked up by the operation of the associated relay PBR only when the route governed by the signal, as designated by the positions of the switch. levers SW, does not conflict with any route governed by another signal clearing relay whichhas been energized.

In case the establishment of a route requires a change in the position of one or more of the track switches, the operated relay PBR completes circuits in Fig. 1G, to pick up a code lockout relay CLO, in each storage unit which governs a switch having its control lever SW out of correspondence with the position of the switch, as refiected by its indication relays NWK and RWK.

In case one or more of the relays CLO become energized, the operated relay PBR completes additional circuits in Fig. IE, to pick up the starting relays ST for the corresponding units, thereby storing codes for operating the switches as required, in addition to storing a code for clearing the signal for the route. In accordance with this feature of our invention, the proper starting relays are selected automatically so as to store for transmission each of theycodes required for the establishment of the desired route in response to a single operation of the starting button STB associated with the operated signal lever SG.

Another result of energizing one or more of the code lockout relay CLO is to open the code initiating and generating circuits, shown in Fig. 1F, controlled by the starting relay for the storage unit which controls the signaLwith the result that the code for clearing the signal will be the .last of those initiated by the operated relay PBR to be transmitted. In accordance with this feature of our invention, the signal clearing code is delayed or locked out by the energized relays CLO, which relays release to permit the transmission of the signal clearing code only when indication codes are received which indicate that each switch of the route has assumed the posi* tion designated by its switch lever SW.

Referring to Fig. 1E, the starting relays 234ST-231ST correspond to those designated 234231 in Figs. 2 and 5 of Patent 2,229,249 and the circuits in Fig. 1F controlled over contacts 0 of the relays ST correspond to those controlled over contacts 0 of relays 234231 shown in Fig. 2 of the patent except for the addition of the lookout circuits referred to.

It is to be understood that these circuits normally function to govern the selection of corresponding storage units at the oflice and station as described in the patent, namely, when one or more of the contacts 0 of the relays ST are closed and connected to terminal B, if the timing relays OLI and 0L2 shown in Fig. 1 of the patent are released, indicating that the code line circuit is free, the master relay OM of the oilice coding unit becomes energized to initiate the transmission of a control code including selecting elements comprising a code call by which a. first for the station storage units are similar to the relays shown in Fig. 7 of the patent and are the relays iS'to i-S shown herein in Fig. 1F.

By reference to Figs. '1 and 2 of the patent, it willbe'seen that'the energization of the selector 'relay' 2358 i releases relay 23G to prevent the 'energization of any additional selector relays by the same code, and as shown herein in Fig. 1E, 'the'energization of the selector relay 2345 also prepares a circuit by which the associated starting relay-EMST'isreleased by the code system relay 08 when the code call is fully transmitted. Each office storage unit is provided with a code indicator relay suchas the relay iCK, shown in Fi'gJIC, which relay ispicked upby the closing of contactb or the associated startingrelay ST when that relay becomes energized to store a control code for transmission, and then is held energized until a return indication code is received from 'the'corresponding' station storage unit. Each relay CK is released by the operation of the delivery relay D of the associated oilice storage unit, such as the relay 23%), which relay, as shown in Fig. 5 of the patent and in Fig. 3 of the accompanying drawings, also operates the officeindication relays INWK, IRWK, etc., in accordance with wayside conditions.

Each relay CK controls a code indicator lamp CKE, which as shown in Fig. 1A, is mounted above the corresponding starting button. Each lamp CKE becomes lighted when the starting relay of the 'unit is energized to store a control code for transmission and remains lighted until a return indication is received from the corresponding station. i1 7 Each lamp CKE is also lighted over contact 9 of the associated selector relay such as relay 234$,

during the reception of an automatically initiated indication code. I v

The circuits for generating the switch control.

elements of a control code, identified by wires Ifil and I03 in Fig.5 of Patent No. 2,229,249, and

those. for generating the signal control elements, 5;

identified by wires I62 and Hi l, are shown in Fig. IE or the accompanying drawings, these circuits as shown being modified in accordance with our invention. When terminal B is connected to one or more or the wires lei-4st during the 7:

transmission or a control code, terminal B at the receiving station is connected to the correspond ing wires 3|-35 of Fig. 2D, and a delivery relay such as relay ID is operated at the end of the code and positions the corresponding group of control relays in accordance with the condition of energization of the wires iii-35 with the same effect as if these were connected directly to the wires Nil-4 94 at the ofiice.

The code elements controlled over wires 19! and I03, by which the switch control relays WSR of Fig; 2D are governed, are controlled jointly by the correspondingly numbered switch levers SW and by the associated code lockout relays CLO of Fig. 1G, as well as by the selector relays S and the track indication relays TK. Additional circuits are provided for energizing wire Ill! or lilii which include the wires 2!, 23, and 2'? and ex tend to terminal B in Fig. 1G over contacts of the. switch levers and indication relays, by which l2 theswitch'control relay WSR may be energized in a direction corresponding to the position. of the track switch indicated by relaysiNWK- and RWK, provided the'switch lever SW is also in a corresponding position. 'It is to be understood, however, that a switch control relay WSEhcam not be energized in the opposite direction, to cause it to assume a non-corresponding position, unless the associated lockout relay CLO isenergized and the associated track indication relay TK is released.

As shown in Fig. 1G, each relay CLO may be picked up under certain conditions, not. only by operation of the relay PBR of another storage unit, as already explained, but also in response to theoperation of the starting button S'IB or its repeating relay PBR for the samestorage unit, provided'the controlling switch lever SW has been moved and the. signal clearing relays controlled by other storage units. which govern route, and also provided'the associated track indication relay is released, indicating that the track section containing the switch is not occupied. This permits the switches to be operated individually'for test purposes or to free them from obstructions, but without energizing the signal clearing relay for any route. Each relay CLO may also be energized under proper conditions along with a signal clearing relay controlled bythesame relay PBR for the purpose of operating a track' switch and clearing a'signal by a single composite code.

The relays CLO also serve to control the route circuits of Fig. 1D so that as soonas a switch operating code is stored for transmission, the energization of a signal clearing relay for any conflicting route is prevented, regardless of the indicated position or the switch.

The code elements controlled over wiresv I02 and IM, by which the signal control relays LHS andRHs of Fig. 2D are governed, are controlled by contacts (1 of the signal clearing relays LGS and RGS, instead of bycontacts of the-signal levers as in the patent. This modification serves to prevent a change in the position of a signal as a result of the operation of any lever other than its control lever,or due to the inadvertent operation'of that lever, without operating the associated starting button.

By reference to Fig. 1D, it will be seen that each signal clearing relay RGS or LGS when picked up is held'energized following the release of the associated'relay- PBR. over'a stick circuit including its own front contacts a and b, andis thereby disconnected from the route circuit over which it was picked up and also from the controlling signal lever SG.

The stick circuit for each signal clearingrelay RGS or LGS is arranged to be opened to release the relay by the opening of contact d of a track indication relay TK when an indication is received that av train has entered the first track section of the route governed thereby, and the signal for such route has been restored automatically to stop. The energized signal clearing relay may also be released to put the signal manually to stop by operating the associated button STB :when the controlling signal lever SG is in its normal center position.

The condition of the signal clearing relays RG8 and LGS is indicated to the operator by including contacts 0 of these relays in the signal indication lamp circuits of Fig. 1B. When'the 1 3 signals 2R and 2L stand at stop, a red lamp ZNE is lighted above the signal lever 23G, and when relay 2LGS or ZRGS becomes energized, a green lamp 2LE or 2RE is lighted along with lamp ZNE. lamp 2NE becoming dark when an indication is received which picks up relay 2LHK or 2RHK, to indicate the clearing of the signals controlled by lever 2SG.

Operation The operation of the system of our invention under different assumed conditions will now be described, starting with the apparatus in the condition shown in the drawing, with all switches normal, all signals at stop, and the detector track sections unoccupied.

It will first be assumed that the operator moves the signal lever ZSG to the right and presses the starting button ISTB associated therewith in order to clear signal ZRA for a train. movement over the route already established which includes the lower main track.

In Fig. 1D, relay IPBR is picked up by the closing of contact a of button ISTB and com pletes a circuit for relay 2RGS from terminal B at the right-hand contact a of lever ZSG over front contact a of relay IPBR through relay ZRGS and thence over back contact at of relay ITK, back contact 7' of relay SCLO, contacts d of levers 33W and 58W and of relays 3NWK and SNWK, contact a of relay SCLO' and contact g of relay 'ICLO to terminal C. In Fig. 1E, the closing of contact of relay IPBR completes a circuit for the starting relay 234ST for the storage unit controlled by the signal lever 28G. Relays ZRGS and 234ST pick up and complete their respective stick circuits, and in Fig. 1F, relay 234ST completes a circuit from terminal 13 at back contact e of relay SCLO over back contacts e of relays 5010 and 'ICLO, front contact 0 of relay ZSGST, back contacts 9' of relays 23G and 2F, back contact a of relay MEP, back contacts b of relays OLI and 0L2 through relay OM to terminal C, whereupon relay OM picks up to indicate. the code transmission in the manner described in the Lewis patent. Relay 234ST picks up relay ICK, Fig. 1C, and the response of these relays is indicated to the operator by the lighting of lamp ICKE over contact b of relay ICK. The red lamp ZNE above lever ZSG is now lighted, and as shown by the circuits of Fig. 1B, the response of relays 2RGS is indicated to the operator by the lighting of the green lamp 2RE, along with lamp ZNE.

I If the operator should now inadvertently reverse lever 35W or SSW, he would open the pickup circuits for the route relay GLGS in Fig. 1D, the one which includes the reverse contact e of lever 3SW being open at back contact a of relay ZRGS. He would also open the circuits for relay GRGS, the one which includes the reverse contact b of lever 58W being open at contact 1 of relay ZRGS and also at contact d of relay 3RWK. However, relays IRGS, SRGS and BLGS may be energized over the route circuits which include normal contacts of lever 33W or 58W to set up routes which do not conflict with the one govcrned by relay ZRGS.

If the operator should reverse one or more of the switch levers SW and press the corresponding starting buttons with a view to operating the switches individually, the code lockout relays 3CLO, 5CLO and lCLO would not respond, and switch control elements eilective to move the switches 3W, 5W and lW would consequently not be included in theresulting codes. The circuit for relay 3CLO, Fig. 1G, controlled over front contact d of relay 3PBR, is now open at back contact n of relay ZRGS while the corresponding circuit for relay 5CLO controlled by contact d of relay 5PBR. is open at back contact 112 of relay ZRGS and also at contact e of relay BRWK, and that for relay 'ICLO, controlled by contact I) of button ISTB, is open at back contact 1 of relay ZRGS and also at contact 1 of relay 3RWK.

It will be seen, therefore, that the operation of the starting button ISTB under the conditions described initiates the transmission of a code for establishing a particular route which cannot be interfered with by the subsequent operation 0 any of the other starting buttons.

It is to be understood that in responseto the code call 234 in the transmitted code relay 234$ at the ofilce becomes energized to prepare circuits in Fig. 1H for generating the switch and signal control elements of the code, and at the corresponding station the selector relay IS operates the delivery relay ID for controlling the relays I WSR, ZLHS and 2RI-IS of Fig. 2D in accordance with the character of these elements. Wire 2| is energized over'a circuit extending from terminal B at contact 0 of lever ISW, Fig. 1G, over front contact c of relay INWK so that in Fig. 1H wire IOI is energized over the circuit extending from wire 2| over contact h of relay 234s and the normal contact a of lever ISW. At the station wire 3|, Fig. 2D, is connected to terminal B in response to the code to cause the energization over contact b of relay ID of the upper winding of relay I WSR, which tends to operate relay IWSR to the normal position which it already occupies. Wire I04, Fig. 1H, is energized by the circuit from terminal B at contact b of relay 234s over contact d of relay ZRGS so that in Fig. 2D relay ZRHS is energized over wire 35 and contact 1 of relay ID. After relay ID releases, relay ZRHS is held energized over a stick circuit including its contact a and back contact b of relay ZLHS and extending to terminal B at back contact (1 of relay ID.

In Fig. 2B, relay ZRHS energizes the route relay ZRH over the circuit from terminal B at back contact 0 of relay ZLI-IS, over contacts a of relays 'INWP, 5NWP, SNWP, INWP, front contact 0 of relay ZRHS through relay ZRH to terminal C.

In Fig. 2C contacts a and e of relay 2RH close to prepare a circuit for mechanism ZRAG, and in Fig. 2G the approach locking relay ZRAS is released by the opening of back contact b of relay ZRH.

In Fig. 2H the opening of contact 0 of relay 2RAS releases the section locking relay IES,and in Fig. ZJ the opening of contact (1 of relay ZRAS releases the switch locking relay I--3LR and the opening of contact 0 of relay IES releases relay 5-'ILR. The relays I3LR and 5-1LR then open their front contacts a, to e in the circuits for the relays WSR and WZ in Figs. 2D and 2E to lock each of the switches of the route, and since in Fig. 20 back contact b of relay ZRAS is now closed, the closing of back contacts 1 of the switch locking relays LR completes the circuit for mechanism ZRAG which extends from terminal B at front contact b of relay 2LAS over contact f of relay 5--1LR, contacts a of relays 'INWP, SNWP, 3NWP and INWP, contact 1 of relay I3LR, back contacts b of relays ZRAS and ZRTE and thence over contacts a and c of relay ZRI-I, contacts b of relays INWP and IRWP and contacts a, b and c of the polarized line relay ZRHD through mechanism ZRAG to terminal C Mechanism ZRAG therefore becomes energized to cause signal 211A to indicate caution or proceed and to release relay'2RGP, which relay opens its .normal position W-henthe operator reversed the signallever;2SG.and pressed the starting button IS'IB in order to clear signalZRA. Theadditional operations required in order to clearthis signal when one or more of the track switches and theircontrol levers are initially in their re- .versepositions. will now be described.

Assuming first thatlever ESW stands reversed andv als o that. relay. lRWK is. energized and relay "l-NWK isreleased, indicating thatswitch IV] is reversed. Inaddition to moving lever ZSG to the right, the operator will restore lever lS-W to nortr al/and then pressb-utton ISTB. In this case relays.2RGS,-;234ST and l CK become energized as already described and, in-addition, a circuit ior relay lCLO, Fig. :lG is .closed by relay IEBR, which circuit extends from terminal B at the normal contact c of lever ISW, back contact of relay INWK, back'contact k of relay PBR, front contact d. of relay IPBR, contact 0 of relay lTK, contact?) of relay SLGS or contact 1 of relay and, contact n of .relay 3CLO, thence through relay ICLO to terminal C. Relay ICLO picks up to, complete astick circuit over its contact, wand the front or'back contact 0 of relay The control code initiated by relay .2.3 lST in this case isa composite code effective to operate relay l-WSR from: reverseto. normal and at the same time to energize relay ZRHS, since in Fig. 1H wire 10! isenergized, over the circuit from ter" minal B at contact e of relay I 'IK, contact. 1 of relay 2343 and contact d oi relay M3150, and wire N14 is energized over contact?) of relay 234s and contact-d. of relay ZRGS. The switch control relays .WSR andthe indicating relays NWP and RWP are relatively quickacting in comparison with the routerelaysRl-I and LH, and although relay JRHS prepares. a circuit for relay ZPJI-I in Fig. 2B,-relay ZRH does not pick up because. contact a'of relay INWP is open and relay lRWPeis released to open its contact a by the openingof the righthandcontact b of relay IWSR. Itfollows thatrelaysZRAS, IES, l-3LR and. 5- -TLR remain energized and relay IWZ isoperated to its normal position by relay lWSRto restore switch LW to normal.

.Referring, now to Fig. 16 it will be seen that the stick; circuit for relay lCLOnow extends to terminal B- at front contact 0 of relay ICK. The ,retum indication code which follows the control code finds relays INWP and IRWP released and so releases relay IRWK,.Fig. 3, to extinguish lamp IRE. Relay ICK releasesto extinguish lamp ICKE and reestablishes the original stick circuit for relay lCLO,.extending to terminal B at contactc of lever lSW. Thiscircuit is so arranged that relay lCLOcannot be released by movement oflever lSW as long as both of the indication relays I-NWK and IRWK are released.

=.As, soon as switch I W completes its movement and is locked in its normal position, relay IWP is operated .to its normal position, energizing. relay lN-Wlgand. then relay ZRH. becomes energized 16 to effect the clearing of signal ZRAas inthepreceding example, and anindication code is transmitted by which relay INWKis energizcd to light lamp INE and to release relay lCLO,.thi-s code also energizing relay ZRHK tQeXtinguish lamp ZN'E as in the preceding example. I

The operations next tobe described are tho s e involved in clearing signal ZRA Whenlever 3Sl/V and the crossover switchespSAW and 3BW initially stand in their reversed positions. In this case, to clear signal ERA, the operator restores leve'r tSW to normal and then rnoveslever 213G to the right and presses button ISTB asin the preceding examples. Contact. d of relay 3NWK', inQthe circuit for relay 2RGS in Fig. 1D previously tracedds now open and relay ZBGS is energized'overback contacth of relay GLGS onlyif theconflicting route governed by relay GLGS is not set up. i

'When relay ZRGS becomes energized, a circuit for relay 3CLO, FiglG, is closed by relay IPBR from terminal B at the normalcontact c ofjlevef'r 35W, over back contact I: of relay :Z-lNWK, front contact k of, relay IPBR, contact n, of relay 2368, back contact 72 of relay ZLGS, through relay 'tChQ to terminal C, and relay 3CLO picksfupto complete a. sticky circuit overits contact a andithe front or back contact c of relay 3CK.' Relays 234ST and ICK, are picked upby relay lPBRjas in the preceding examples, and, in addition, a circuit is closed, in FigQlEfrom terminal B at contact g of relay IPBR over contact 1) of relay 3CLO to pick up relay 235 ST, which in turn picks up relay SCK so that lamps lCKE and'tCKE are'both lighted. Relay Z35ST initiates the transmission of a code for operating the switch control relay SWSR to normal in, which wire llll FigilHlis energized over. contact, f of relay 235s and contact d of relay 3CLO, but relay ZIMST, although picked up, is prevented from transmitting the signal clear n ce au h c de n t insla d se ierating circuit in Fig 1F, which relay23 4S1T controls, is held open at, back contacts e of,.1felays more and acne.

In Fig. 1D, contact 1 of relay .ZRGS in the route circuit for relay ERGS is. open, consequently the opening of contact f of relay 3CLO' in parallel therewith, and the opening of contact (1 of relay 3RWK by the indication code which follows. the control code for operating switches SAW and 313W to normal, prevents theenergizationofrelay SRGS to set up the conflicting route iromfsignal 6R to signal GLA or fiLB. Likewise, the opening of contact hof relay SCLO prevents themergization of relay ELGS, and the opening of conenergization of relay GRGS.

In Fig. 1G, the back contacts 1 andm of relay ZRLGS in the circuits for relays 'l;CLO,,and 5CLO are open, and the opening of contacts! and m of relay 3CLO in parallel therewith, .followed by the openingof contacts 1 and e, respectively, of relay 3RWK, prevents the individual operation of thecorresponding switches by pressing button 'lS-TBor ESTIB. ,However, ifswitches 3AW and SBW fail to assume their normalposition promptly, they may be operated individually to reverse or normal as required ,because relay 3CLO will beheld energized irrespective offthe position of lever SSW as long as relays and SRWK remain released, as already explained in connection withlever ISW.

When. switches SAW and BBW assume their normal position, relay. 3NPW takes up to preparefa route circuit. for relay. ZRH and to initiate an indication code to energize relay 3 NWK,- ther e' tacts gof relays ZRGS and 3CLO preventsthe v releasing relay 3CLO, which by closing its back contact e, Fig. 1F, completes the code initiating circuit controlled by relay 234STto initiate the transmission of the signal clearing code.

When lever 58W or 'ISW stands reversed, the

operations involved in the clearing of signal ZRA .are similar to those described in connection with lever SSW except that the starting relay for initiating the switch control code is energized .by relay 5CLO or 'ICLO. When the crossover switches 5A-5B are reversed, contact d of relay ENWK in the circuit for relay ZRGS is open and relay ZRGS may be energized over back contact h of relay GRGS only if the conflicting route governed by relay 5RGS is not set up, and when relay IRGS is energized the opening of its back contact j prevents the energization of relay GRGS to establish this conflicting route.

It is to be noted that switch lW is included in routes governed by relays 2RGS, ZLGS and tRGS, but that relays ZRGS and ESRGS also govern other routes which do not include switch lW. By reference to Fig. 1G, it will be seen that relay l'CLO may be picked up over contact h of relay EPBR and. contact I of relay ZRGS only when lever 3SW is normal and its contact g is closed, and similarly, relay 'I'CLO may be picked up by relays 5PBR and ERGS only when the reverse contact a of lever 58W is closed. It follows that relay lCLO responds to the operation of relay IPBR or SPBR only when the route being established includes switch 'IW. From Fig. IE it will be seen that the starting relay 237ST is energized by relay IPBR over the normal contact h of lever 35W or by relay ESPBR over the reverse contact h of lever ESW only when the route being established includes switch 7W. When relay lCLO is energized, its open back contacts f, y and h, in Fig. 1D, prevent the energization of relays ERGS, 2RGS and ZLGS, respectively, to establish a conflicting route over switch 1W, but the circuits are arranged to permit relay ZRGS to be energized over the reverse contact of lever 38W, or relay BRGS to be energized over the normal contact I) of lever 53W to establish a non-conflicting route. Furthermore, the opening of contact 71. of lever SSW or ESW in Fig. 1E. prevents the transmission of a code for operating switch IW in response to the operation of re lay HPBR or PBR except when switch lW is included in the route being set up.

It has already been pointed out in connection with certain of the routes governed by relay ZRGS that the code initiating and generating circuits of Fig. 1F are held open by the relays CLO so as to lock out or delay the transmission of the signal clearing code until the indicated position of each switch of the route controlled by a different storage unit is in agreement with the position of its control lever. By reference to Fig. 1F it will be seen that the circuits are arranged as required to attain this result in the case of each of the routes. For example, when relay ZRGS is energized with lever SSW reversed to set up the route from signal ZRB or 2R0 to signal 6R, the circuit for initiating the signal clearing code includes contact 0 of relay 23481 and is completed over front contact e of relay 2RGS following the operation of switches 3AW and 3BW to reverse as indicated by the closing of contact g of relay 3RWK and contact e of relay 3CLO. It will be noted that this circuit is opened by relay 3CLO upon the initiation of a code for operating the switches 3AW and 33W to normal,

prior to the release-of relay 3-RWK, and that when relay BRWK releases, back contacts e of relays 5CLO and 'ICLO- are included in the circuitby which the signal clearing code is initiated. This is for the reason that each of the remaining routes governed by relay ZRGS and all routes governed by relay ZLGS include the switches governed by relays ECLO and lCLO in addition to those governed by relay 3OLO. 1.

Furthermore, when relay BLGS is energized, an initiating circuitfor the code for clearing signal BLA 0r fiLB is prepared in Fig. 1F which includes contact 0 of relay 23BST, back contact 6 of relay IiRGS, back contact 0 of relay 30110 and contact 9 of relay BNWK or contact 0 of relay lCLO. It follows that this code is locked out by the opening of contact 0 of relay SOLO if the operation of switches 3AW and 3BW to normal or reverse is required in order to set up the route, and also by contact 0 of relay ICLO if these switches have already been reversed so that the designated route includes switch I W. When relay (iRGS is energized, relay GLGS is released, and the initiating circuit controlled by relay NEST in Fig. 1F includes contact 0 of relay ICLO or contact c of relay ECLO and contact is of relay SNWK, and extends to terminal 13 at back contact e of relay GLGS. It follows that the code for clearing signal GR is locked out by contact 0 of relay 'ICLO and contact I: of relay ENWK when switches 5AW 5BW stand reversed, or by contacts 0 of relays 'ECLO and lCL O if the operation of these switches to reverse is required to set up the designated route. I I

It will now be assumed that signal 2RA, 2RB or Z RC has been cleared, but that a train accepts the signal and enters section IT before an indication of the clearing of the signal is transmitted by the remote controlsystem. In this case the track storage relay lTS, Fig. 3, will be held energized until an indication of the occupancy of section IT is transmitted even though the train passes out of this section and reenergizes the track relay iTR. Relay ZRHS, Fig. 2D, will have been released by the opening of contact a of relay I'TR, releasing relay ZRH to return the signal to stop when the train enters section IT, but the operator will be unaware ofthis and it may be that he will retransmit the signal clearing code by reoperating the starting button ISTB. It will be seen that relay ZRH S will not respond to this code even though the train has vacated section IT, due to the opening of contact d of relay ITS in its circuit. The next indication code will include elements, indicating the occupancy of section IT and the return of the signal to stop, relay lTK becoming energized to light lamp ITKE and to release relay ZRG'S, thereby extinguishing lamp Z-RE and lighting lamp ZNE, whereupon the operator will return lever ESG to normal, thereby restoring the apparatus to the condition shown in the drawings. It may be that the signal clearing code referred to is a composite code for operating switch IW as well, in which case it may happen that the operator will assume that the switch failed toretion of the wayside locking circuits provided to 3. B to reverse, in and 3CLO are energized. 1 -Whenrelay JCL-O picks up, the opening of its back contact. f, in Fig. 1D, prevents the energization of relayBLGS to set up a route over switch 1W; andirelay lCLO is held energized by relay tryefit the operation of a switch under atrain. In other words, if relay I'IR should become energized-momentarily due to poor shunting of the track rails by a train in section IT, so as to pick up relay I3LR preciselywhen a code impulse "-for operating relay IWSR is received, the code is "rendered ineffective by the opening of contact 0 of relay ITS. Relay ITS is released when a code indicating the occupancy of section IT is transmitted. This code will energize relay ITK thereby opening its contact e in the circuits leading to wires Hll and H13 so that a control code for changing the'position or" the switch 1W cannot be transmitted. This indication code will also eneradditional protection train over that heretofore available.

It will next be assumed that the operator reverses the switch lever ISW and presses button lSTB with the signal lever ZSG in its .normal ,.center position. in order to operate switch IW individually;

In this case, in response to the energization of relay IPBR by. the starting button ISTB, relay [CLO is energized over the circuit from terminal B atthe reverse contact 0 of lever LSW, over back contact cof relay IRWK, back contact is of relay 5PBR, frontcontact d of relay IPBR, contact 0 of relay ITK and contact I) of relay BLGS or contact ,f of relay 3NWK and contact n of relay SOLO through relay ICLO to terminal C.

It will be evident that the circuit just traced is unavailable if the route over switch IW governed by relay 'GLGS is set up, in which case relay BLGS is energized and relay 3NWK is released, and is likewise unavailable if this route is being established by the operation of the crossover switches which case relays BLGS ICK; from the time the switch control code is stored for transmission until a return indication is received, as in the preceding examples.

J'Ihe operation of each of the remaining switches individually may be carried out in a switch controlled from any panel except the one from which the operated switchis governed.

, It is to be understood that the chance that an operator would inadvertently move a reversed signal lever to its opposite position or that he would reverse the switch lever of a panel and press the starting button while the signal lever is reversed is considered so remote that it is unnecessary to interlock the two signal clearing relays RGS and LGS controlled by the same lever or to control them by the lockout relay CLO of the same panel, and that the purpose of the interlocked lever circuits as shown herein is primarily to provide protection against improper manipulation when the levers involved are in different panels.

In the foregoing the operations described in detail have been principally those relating to the apparatus governed from "the first panel controlled by the starting button ISTB, but since the operation of the apparatus of theother panels functions in a generally similar manner, it is believed that this will be understood, and further, that the operation of the apparatus of our invention as applied to track layouts whichdifier from the one shown will also be understood without further description;

Although we have herein shown and described only one form of apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In combination with a track switch and a signal for governing trafiic movements over the switch, switch and signal levers at a remote control office, a switch control relay for operating the switch, a signal control relay for controlling the signal, a code system for transmitting control codes for operating the switch control relay in accordance with the position of the switch lever at said control oifice and for transmitting other codes for operating the signal control relay in accordance with the position of the signal lever at said office, switch indication means at the ofiice for indicating the position of the track switch, a code lockout relay controlled by said indication means and said switch lever, means forpactuating said code lockout relay when the transmission of a code by said code system for clearing said signal is manually initiated provided the position of the switch indicated by said switch indication means does not correspondwith the position of the switch lever, means controlled by the code lockout relay when actuated for causing said code system to transmit a code for'operating the switch to the position designated by the switch lever and for storing said initiated signal clearing code for transmission following restoration of said code lockout relay to normal, and means for maintaining saidcode lockout relay actuated from the time said switch control code is initiated until said switch indication means is operated to indicate that the switch has assumed the position designated by said switch lever.

:2. In combination with a plurality of track switches and a signal for governing trafilc movements over a route including said. switches, a switch lever for each switch and a signal lever for said signal at a control office, a code system for transmitting distinctive codes for selectively operating said switches in accordance with the positions of the switch levers at said control oflice and for transmitting a different code for controlling said signal in accordance with the position of the signal lever at said office, switch indication means at the ofiice for each switch for indicating its position, a code lockout relay at the ofiice for each switch, a starting button associated with said signal lever effective when actuated to initiate the transmission of said code for controlling the signal'and for also actuating the code lockout relay for each switch the indicated position of which does not correspond with the position of its switch lever, means controlled by each actuated code lockout relay for causing said code system to transmit a code for operating the corresponding switch to the position designated by its switch lever and for delaying the transmission of the initiated signal controlrcode as long as such code lockout re1ayremains...aq-

21 tuated, and means for maintaining each actuated code lockout relay actuated until the switch indication means for the corresponding switch indicates that such switch has assumed the position designated by its switch lever.

3. In combination with a track layout including a plurality of track switches adapted to be arranged to form different traffic routes with signals for governing trailic movements over the routes, a code system for selectively operating said switches and signals from a control office, signal levers and signal clearing relays controlled thereby for governing the transmission of signal clearing codes by said code system, switch levers and code lockout relays controlled thereby for governing the transmission of switch control codes by said code system, switch indication means at said oliice for indicating the positions of said switches, a plurality of starting buttons including one for each signal lever for initiating the operation of said code system, means responsive to the operation of any starting button when the associated signal lever is reversed for immediately actuating the signal clearing relay associated therewith provided the switch levers occupy positions designating a route governed by the signal which such signal clearing relay controls, irrespective of the positions of the switches in such route, and also provided no signal clearing relay for a signal governing a conflicting route is actuated, means controlled by the operated starting button and the associated signal clearing relay when actuated for actuating the code lockout relays for only those switches of the designated route the indicated position of which does not correspond to that of their switch levers, means controlled by the operated starting button and the actuated code starting relays for causing said code system to transmit codes for operating each switch having its code lockout relay actuated and for clearing the signal having its signal clearing relay actuated, and means controlled by the actuated code lockout relays for delaying the transmission of said signal clearing code until indications are received that the corresponding track switches in said route have assumed the positions. designated by their switch levers.

4. In combination with a railway track switch, indication means at a control ofiice for indicating the position of the switch, a switch lever at the office for controlling the switch, a code system adapted when initiated to transmit a code for operating the switch to a position designated by the switch lever at said oflice, a code lockout relay at said office, means for causing said code lockout relay to assume an operated position when the transmission of a code by said code system is initiated provided the switch position designated by said switch lever does not agree with that indicated by its indication means, means efiective only when said code lockout relay assumes its operated position for rendering the transmitted code eiiective to operate the track switch from its indicated position to the opposite position, and means controlled by the operation of said indication means following the transmission of said code for restoring said code lockout relay to its normal position provided the position of the switch indicated thereby corresponds with the position of said switch lever.

5. In combination with a railway track layout including a track switch and signals for governing traiiic movements over the switch, switch and signal levers and signal clearing relays controlled by said signal levers at a control offlce, a code system adapted when initiated to transmit codes for clearing any one of said signals when the corresponding signal clearing relay is actuated and for operating said switch to the position designated by said switch lever, indication means at said oflice for indicating the position of the switch, a code lockout relay, means for causing said code lookout relay to assume an operated position when the transmission of a code by said code system is initiated provided the switch position indicated by said indication means does not correspond with the position designated by said switch lever, means rendering the resulting code effective to operate the track switch only if said code lockout relay assumes said operated position, means responsive to the operation of said indication means following the transmission of said code for restoring said code lockout relay to its normal position provided the switch position indicated by said indication means corresponds to the position designated by said switch lever, and means comprising a system of route circuits which conform to the routes over said track switch and include contacts closed only when said code lockout relay occupies its normal position, for selectively actuating said signal clearing relays only one at a time, said circuits being so arranged that each such relay is selected for actuation by the reversal of the corresponding signal lever and becomes actuated upon the initiation of a code for clearing the signal which such lever controls only if the route governed thereby does not conflict with any route governed by another signal for which the signal clearing relay is actuated.

6. In combination with a railway track layout including a track switch with signals for governing traffic movements over the switch, switch and signal levers at a control ofiice, a code system adapted when initiated to transmit a first distinctive code for clearing a signal designated by the reversal of its signal lever or to transmit a second distinctive code for operating the switch to the position designated by said switch lever, a first and a second starting button for manually initiating the transmission of said first and second distinctive codes, respectively, by said code system indication means at said office for indicating the position of the switch, a code lockout relay, means for causing said code lockout relay to assume an operated position in response to the operation of said first or second starting button when the transmission of said first or second distinctive code is initiated, provided the switch position indicated by said indication means dces not correspond with the position designated by said switch lever, means controlled by said code lockout relay and eiiective if said code lockout relay assumes its operated position upon the initiation of said first distin tive code, when said first starting button is operated, for delaying its transmission and for initiating and causing the prior transmission of said second distinctive code, and means for restoring said code lockout relay to its normal position to enable the transmission of said first distinctive code to be efiected when the switch position indicated by said indication means corresponds to the position designated by said switch lever.

'7. In combination with a railway track layout includinga track switch with signals for governing trafiic movements over the switch, a code systern-for transmitting codes for controlling the scrapes track switch and-signals in accordance with the positions of switch and signal levers and for also controlling indication mean for indicating the position of the switch, a first starting relay effective when operated to close an initiating circuit which when closed causes the system to transmit acode for controlling the track switch, a second starting relay controlling another initiating circuit effective when'closedto cause said'code system to transmit a code for controlling said signals, a first starting button associated with said switch lever for operating said first starting relay, a second starting button associated with said signal lever for operating said second starting relay, means responsiveto the operation of said second starting button when said s gnal lever is in its signal clearing position but the indicated position of the track switch does not correspond to that ofthe switch lever for operating both said starting relays, and means controlled by said indication means for delaying the closing of the initiating circuit controlled by the second starting relay until the indicated position of the track switch corresponds to that of said switch lever.

8.-In a centralized trafiic control system, a

. detector track section including a track switch, a track relay which is released when said detector section is occupied, a control relay for the switch, a code type communication system connecting the switch location with a control office, means for causing said communication system to transmit switch control codes for operating said control relay in accordance with the position of a switch lever at the olfice, a storage relay controlled by the track relay, means including said storage relay for causing said communication system to transmit indications of the occupancy 9. In a centralized traffic control system, a

detector track section includinga track switch, a track relay which is released When said detector 1 section is occupied, a control relay for the switch,

a code typecommunication system connecting the switch location with a control ofiice, means ,"I

for causing said communication system to transmit switch control codes for operating said control relay in accordance with the position of a switch lever at the office, a storage relay controlled by the track relay, means including said storage relay for causing said communication system to transmit indications of the occupancy of said track section to the ofiice and for storing such indications until transmitted, a track indication relay at the oflice controlled by the-indications transmitted by said code system for indicating the occupancy of said track section, means for preventing the response of said control relay to a switch control code transmitted when said track relay is released or when an indication of the occupancy of said detector track section is stored by said storage relay, and means controlled by said track indication relay for preventing the transmission of a code for operating said control relay when said indication relay indicates the occupancy of said detector track section.

10. In a remote control system of the type having an oifice and a plurality of field stations including a first and a second field station, the equipment at the omce including a code transmitter for; transmitting different codes to said stations each comprising a first group of elements adapted to select a, station and a second group both actuated to transmit a code to said first,

field station and to thereafter transmit a code to said second field station, the combination with the foregoing apparatus of a track switch governed through said second field station in accordance with the position of a switch lever at said ofiice, a signal controlling traffic over said switch and governed through said first field station in accordance with the position or" a signal lever at said ofiice, switch indication means at said office governed in accordance with the position of said track switch, a first starting button associated with said signal lever and a second starting button associated with said switch lever for actuating said first and second starting relays'to initiate transmission of codes to the corresponding stations, and means at said otfice efiective only when said first starting button is actuated while said signal lever is in its clear position and said switch lever is out of correspondence with said switch indication means for actuating said second starting relay and for controlling said code transmitter to cause it to transmit the code for said second field station before it transmits the code for said first field station.

11. In a remote control system of the type 'havingan office and a plurality of field stations including a first and a second field station, the equipment at the ofiice including a code transmitter for transmitting different codes tosaid "stations'each comprising a first group of 'elements adapted to select a station and a second group of elements for operating movable devices at the selected station, the equipment at the ofiice including a first starting button effective when actuated to condition said code transmitter to transmit a control code to said first field station and a second starting button effective when actuated to condition said code transmitter to transmit a control code to said second field station, said code transmitter when conditioned to transmit control codes to said first and second field stations normally operating to transmit the control codes to said first field station before operating to transmit the control code to said second field station, the combination with the foregoing apparatus of a track switch governed through said second field station in accordance with the position of a switch lever at said ofiice, a signal controlling traific over said switch and governed through said first field station in accordance with the position of said track switch, and means at said oflice effective only when said first starting button is actuated while said signal lever is in its clear position and said switch lever is out of correspondence with said switch indication means for conditioning said code transmitter to transmit a control code to said second field station and to do so before it transmits a control code to said first field station.

to said first and said second 12. In a remote control system of the type having an ofiice and a pluraiity field stations including a first and a second field stat n, the equipment at the office including a code mitter for transmitting different codes to said stations each comprising a first of ments adapted to select a station and a second group of elements for operating movable devices at the selected station, the equipment at the office including a first starting button effective when actuated to condition said code transmitter to trans mit a control code to said first field station an d. a second starting button effective when actuated to condition said code transmitter to transmit code to said second field station, said code trans mitter when conditioned to transmit control codes stations mally operating to transmit the control code to said first field station before operating to transmit the control code to said second. field station, the combination with the foregoing ap paratus of a second control relay governed through said second field station in accordance with the condition of a control circuit at said ofiice, a first control relay governed through said first field station in accordance with the position of a signal lever at said office, a signal governed jointly by said first and second control relays, and means at said ofiice effective only when said signal lever is in its clear position for conditioning said code transmitter to transmit a con trol code to said second field station and to do so before it transmits a control code to said first field station.

13. In a remote control system of the type having an oflice and a plurality of field stations in- Cluding a first and a second field station, the equipment at the oifice including a code transmitter for transmitting diiierent codes to said stations each comprising a first group of elements adapted to select a station and a second group of elements for operating movable devices at the selected station, the equipment at the office including a starting relay for each station, each starting relay being effective when actuated to render effective a circuit governing the code transmitter to cause a code to be sent to the corresponding station and being restored to normal in consequence of transmission of a code to the corresponding station, the equipment at the ofiice normally operating when the starting relays for said first and second field stations are both actuated to transmit a code to said first field station and to thereafter transmit a code to said second field station, the combination with the foregoing apparatus of a first control relay governed through said first field station in accordance with the position of a signal lever at said oflice, a second control relay governed through said second field station in accordance with the condition of a control circuit at said ofiice, a railway signal controlled by said first and second control relays and governing movement of traffic over a selected track stretch, a first starting button for actuating said first starting relay to initiate transmission of a code to said first field station, a second starting button for actuating said second starting relay to initiate transmission of a code to said second field station, means at said oifioe effective only when said first starting button is actuated while said signal lever is in its clear position for actuating said second starting relay, and means for rendering said first starting relay incapable of conditioning said code transmitter to transmit a 26 code to said first field station while said second starting relay is actuated and said signal lever is in its clear position.

14. In a remote control system of the type having an ofiice and a plurality of field stations including a first and a second field station, the equipment at the office including a code transmitter for transmitting different codes to said stations each comprising a first group of elements adapted to select a station and a second group of elements for operating movable devices at the selected station, a first starting relay efiective when actuated to establish a first operating circuit governing the code transmitter to cause a code to ls-e sent to said first field station, a second starting relay effective when actuated to establish a second operating circuit governing the code transmitter to cause a code to be sent to said second field station, each of said starting relays being restored to normal in consequence of transmission of a code to the corresponding station, the equipment at the office normally operating when the starting relays for said first and second field stations are both actuated to transmit a code to said first field station and to thereafter transmit a code to said second field station, the combination with the foregoing apparatus of a first control relay governed through said first field station in accordance with the condition of a signal lever at said control ofiice, a second control relay governed through said second field station in accordance with the condition of a control circuit at said office, a railway signal controlled by said first and second control relays and governing movement of trafiic over a selected stretch of railway track, a first starting button for actuating said first starting relay to initiate transmission of a code to said first field station, a second starting button for actuating said second starting relay to initiate transmission of a code to said second field station, means at said oifice effective only when said first starting button is actuated while said signal lever is in its clear position for actuating said second starting relay, and means governed jointly by said second starting relay and by said signal lever for preventing establishment of said first operating circuit by said first starting relay while said signal lever is in its clear position and said second starting relay is actuated, whereby operation of said first starting button which results in actuation of said first and second starting relays causes said code transmitter to trans mit codes to said first and second field stations in the reverse of the normal sequence.

FRANK T. PASCOE. ARTHUR L. JEROME.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,141,074 Young Dec. 20, 1938 2,229,249 Lewis Jan. 21, 1941 2,265,240 Langdon Dec. 9, 1941 2,302,038 Langdon et al. Nov. 17, 1942 2,331,262 Young Oct. 5, 1943 2,343,784 McCann et a1 Mar. 7, 1944 2,404,303 Law July 16, 1946 2,411,387 Pascoe et a1 Nov. 19, 1946 2,420,579 Young May 13, 1947 

